President Trump is narrowing search of op-ed author who claims there's a "resistance" within the White House. (NICHOLAS KAMM / AFP/Getty Images)

White House aides are reportedly homing in on a small group of suspects in their search for the unnamed author of an op-ed claiming there’s a cabal of administration officials who believe President Trump is unfit for office.

Trump is “obsessed” with finding the author of the piece, CNN reported Saturday, a day after the President said he knows “four or five” people who could be the “senior official” behind the bombshell published last week by The New York Times.

Advertisement

He believes it is “somebody in national security,” White House counselor Kellyanne Conway told CNN on Friday.

Trump has called on Attorney General Jeff Sessions to investigate the anonymous senior official’s identity, citing national security concerns.

“We’re going to take a look at what he had, what he gave, what he’s talking about also where he is right now,” Trump told reporters Friday on Air Force One.

"It's national security," he added.

Dozens of top Trump administration officials, including Vice President Pence, have denied being behind the work.

The unknown author claims that he, or she, and other Trump aides are “working diligently from within to frustrate parts of his agenda and his worst inclinations” and “thwarting Mr. Trump’s more misguided impulses until he is out of office.”